Neurological Syndromes Associated with Congenital Absence of the Odontoid Process

Introduction Although there has been a considerable interest recently in neurological syndromes associated with congenital malformations of the cervical spine and basiocciput,1,2absence of the odontoid process has not been emphasized. We have been able to find only 13 reports of this condition, describing a total of 15 patients.3-15Two cases occasionally included in discussions of this syndrome have been omitted from this report because a significant portion of the odontoid process was present (Cases 4 and 168). This condition is more than a medical curiosity, since six patients have had transient neurological symptoms5,7,8,11-13and permanent signs of cord damage have occurred in three.8,9,15Because previous reports have been concerned with the radiologic and orthopedic aspects, the following two cases are reported to show that this skeletal anomaly should be considered in the differential diagnosis of cervical myelopathy. Report of Cases Case 1. —A 59-year-old man